Use of pitch battery power to start wind turbine during grid loss/black start capability

Abstract

The disclosure concerns a wind power plant and its operation during grid loss, wherein the wind power plant comprises a plurality of rotor blades, a blade pitch drive, a rotor shaft, an electric generator, and a control unit for controlling the operations of the wind power plant, wherein the plurality of rotor blades are rotatably connected to the rotor shaft, such that the pitch of the rotor blades can be adjusted by the blade pitch drive under the control of the control unit, and wherein the rotor shaft is operatively connected to the electric generator for generating electric energy, the wind power plant further comprising an energy storing unit for powering the blade pitch drive, wherein the control unit comprises a control module for adjusting the rotor blades and for entering a self-sustaining mode of operation of the wind power plant. With the self-sustaining mode of operation basic functions of the wind power plant, in particular safety and security functions as well as lubrication of the rotatable parts of the wind power plant are sustained even for long periods of a grid loss.

1. Method of operating a wind power plant during grid loss, the method comprising
 powering a blade pitch drive of the wind power plant by an energy storing unit and 
 adjusting the pitch of rotor blades of the wind power plant by means of the blade pitch drive,
 wherein a rotor shaft keeps rotating and the wind power plant enters a self-sustaining power generating mode upon adjustment of the pitch of the blades. 
 
 
     
     
       2. Method according to  claim 1 , further comprising
 generating electric energy with an electric generator and recharging the energy storing unit therewith. 
 
     
     
       3. Method according to  claim 1 , further comprising
 detecting the occurrence of grid loss, 
 reducing the amount of energy being generated by an electric generator by adjusting the pitch of the rotor blades and 
 entering a self-sustaining mode of operation of the wind power plant. 
 
     
     
       4. Method according to  claim 1 , the method, in case of grid loss and low wind speeds, further comprising
 detecting a current wind speed, 
 comparing the wind speed with a threshold, and 
 if the wind speed is above the threshold, entering a self-sustaining mode of the wind power plant by adjusting the pitch of the rotor blades. 
 
     
     
       5. Method according to  claim 1 , comprising
 measuring the charging level of the energy storing unit and 
 stopping the rotation of the rotor shaft, if the charging level drops below a charging level threshold. 
 
     
     
       6. Method according to  claim 1 , further comprising
 powering down at least a portion of a control unit of the wind power plant if the wind speed drops below a first wind speed threshold, and 
 waking up the portion if the wind speed exceeds a second wind speed threshold. 
 
     
     
       7. Method according to  claim 1 , further comprising
 generating electric energy with an electric generator and recharging the energy storing unit therewith. 
 
     
     
       8. Method according to  claim 1 , further comprising
 detecting the occurrence of grid loss, 
 reducing the amount of energy being generated by an electric generator by adjusting the pitch of the rotor blades. 
 
     
     
       9. Method according to  claim 1 , the method, in case of grid loss and low wind speeds, further comprising
 detecting a current wind speed, 
 comparing the wind speed with a threshold, and 
 if the wind speed is above the threshold, entering or maintaining a self-sustaining mode of the wind power plant by adjusting the pitch of the rotor blades. 
 
     
     
       10. Method according to  claim 1 , comprising
 measuring the charging level of the energy storing unit and 
 stopping the rotation of the rotor shaft, if the charging level drops below a charging level threshold. 
 
     
     
       11. Method according to  claim 1 , further comprising
 powering down at least a portion of a control unit of the wind power plant if the wind speed drops below a first wind speed threshold, and 
 waking up the portion if the wind speed exceeds a second wind speed threshold. 
 
     
     
       12. Method according to  claim 1 , wherein the rotation shaft is lubricated upon rotation. 
     
     
       13. Method according to  claim 1 , wherein the rotation shaft is lubricated upon rotation.